Arrangement for proportioning actively or passively light-radiating surfaces

ABSTRACT

An arrangement for displaying characters or symbols on a screen of a display device where characters selected by comparing a predetermined area of the displays stored in a memory with a counter circuit controlled by a column counter, a character counter, a scan line counter and a reading line counter inverts the selected characters in an inverter stage connected between a character generator and the display device.

United States Patent Schroder et al.

1541 ARRANGEMENT FOR PROPORTIONING ACTIVELY OR PASSIVELY LIGHT-RADIATINGSURFACES [72] Inventors: Jurgen Schroder, Hamburg; Hans Georg Nussbaum,Bremen, both of Germany 73] Assignee: U.S. Phillps Corporation, NewYork, NY. [22] Filed: Mar. 17, 1970 [21} Appl. No.: 20,371

301 Foreign Application Priority Data Mar. 22, 1969 Germany ..1 19 14764.9

[52] US. Cl. ..340/324 A, 340/ 172.5 [51] Int. Cl. ..G06f 3/14 [58]Field of Search ..340/324, 324 A, 324 R, 172.5

[45] Mar. 7, 1972 [56] References Cited UNITED STATES PATENTS 3 ,505,665 4/ l 970 Lasoff et al. ..340/ 324 3,432,846 3/1969 Jones et al...340/324 3,292,154 12/1966 Simmons ..340/324 3,466,645 9/1969 Granberget al. .....340/324 3,346,853 10/1967 Koster et al ..340/324 PrimaryExaminer-John W. Caldwell Assistant Examiner-Marshall M. CurtisAttorney-Frank R. Trifari [57] ABSTRACT An arrangement for displayingcharacters or symbols on a screen of a display device where charactersselected by comparing a predetermined area of the displays stored in amemory with a counter circuit controlled by a column counter, acharacter counter, a scan line counter and a reading line counterinverts the selected characters in an inverter stage connected between acharacter generator and the displaydevice.

8 H ZEBETSLM Patented March 7, 1972 6 SheetsSheet 1 INVENTORS NUSSBAUMBY J SCHRODER H. G.

AGENT Patented March 7, 1972 6 Sheets-Sheet 2 INVENTORS SCHRODER H. a.NUSSBAUM BY #1, ,6

AGENT Patented March 7, 1972 3,648,272

6 Sheets-Sheet 5 AGENT Patented March 7, 1972 6 Sheets-Sheet 4 NVENTORFJ SCHRODER H. G. NUSSBAUM BY W AGENT Patented March 7, 1972 6Sheets-Sheet 5 ZchZ DSP

INVENTORLS cCHRODER NUSSBAUM AGENT patenteti March 7, 1972 6Sheets-Sheet 6 INVENTORJ SCHRODER G. NUSSBAUM J. H. BY

ARRANGEMENT FOR PROPORTIONING ACTIVELY OR PASSIVELY LIGHT-RADIATINGSURFACES The invention relates to an arrangement for proportioningactively or passively light-radiating surfaces by means of adjustablesuperpositions and variations in brightness on these surfaces on whichcharacters or symbols are periodically produced with the aid of acontrol stage by means of control signals for a character generatorwhich control signals can be read out from a store and counted bycolumn, character, scanning line and reading line counters, whichgenerator provides modulation voltages as character control signals forthe purpose of causing the light-radiating surfaces to light up.

In modern electronic data-processing devices increasing use is beingmade of equipment based on the action of light for feeding andextracting data which are used to exchange information between man andmachine in an easier and quicker manner. When this information isdisplayed in the form of symbols, signs and/or characters on alight-radiating surface a convenient arrangement for satisfactoryreadability is of great importance. A convenient display is possiblewith the aid of a given proportioning of the overall image. In additionit is very advantageous when it is possible for the user of theapparatus to accentuate certain pieces of information relative to therest of the picture contents in order to draw his attention, forexample, to very important pieces of information on the image surface.

In the apparatus known so far certain signs or groups of signs areaccentuated by means of a blinking" display, that is to say, to theviewer the intensity in brightness on the image surface seems to vary ina rhythm of approximately 1-10 Hz. at which the light-dark ratio may bechosen differently. However, this method is not very advantageous sincethe flickering signs may irritate the viewer and give the overall imagea jittery impression. There are also methods wherein separate symbols ofthe signs are accentuated by underlining them which, however, is alimited step as regards a clear characterization.

An object of the present invention is to accentuate areas which arepermanently adjustable or are chosen by control information on thelight-radiating surfaces by means of a given brightness in contrast withthe other areas having symbols. This is solved in the above-mentionedarrangements which to this end are characterized in that in addition tothe character control signals modulation voltages are derived from theoutput signals of the column, character, scanning line and reading linecounters, which output signals can be chosen directly or through thecontrol stage which is controlled by the memory, and that an inverterstage is provided behind the character generator.

The means generating the active or passive light is driven line by lineor column by column over the overall range of the light-radiatingsurfaceupon which the symbols, characters or figures must be displayed.

The information to be displayed is used as a picture signal for thecontrol of the intensity of the means producing the light radiation. Thesymbols accentuated in the picture areas may be inverted automaticallyinto their brightness intensity, that is to say, generally dark picturedots serving for the display can be inverted into bright picture dotsand bright picture dots can be inverted into dark picture dots.

In the arrangement according to the invention it is particularlysuitable toinsert permanently strips or lines accentuated by adifferentbrightness between characters arranged in lines so that a horizontaldivision of the overall picture is obtained for thepurpose of betterreadability.

Furthermore, a picture impression which is pleasant to the eye can beobtained by means of a slight increase of the brightness of the overallpicture background which appears as a weak grey background. This iseffected in a simple manner by the addition of a constant signal to thepicture signal.

To explain the invention hereinafter the screen of a cathode-ray tube isused as the actively lightradiating surface and the electron beam of acathode-ray tube is used as the means causing the light radiation (lightconduction).

However, it is alternatively possible to use a passively lightradiatingsurface which is irradiated by a digital light-deflectionarrangementactive as a light source. In this case, however, all lines of thesurface are composed of closely spaced dots possibly modulated inbrightness while coherent scanning and reading lines are also availablein an actively light-radiating surface.

A few examples are described with reference to FIGS. 1-7 of the drawingsin order to show the possibilities of proportioning the pictureaccording to the invention.

FIG. 8 shows a block diagram of an arrangement with the aid of whichcharacters and symbols can be displayed on the picture screen of acathode-ray tube while FIGS. 9-13 show embodiments of the inventionwhich, added to the arrangement according to FIG. 8, permit the displayof the proportioned pictures.

DISPLAY or A CURSOR A cursor marks the position where symbols orcharacters supplied by the viewer, for example, through a keyboard areto be written on the picture screen.v In case of corrections of the textthe viewer moves the cursor to the position to be corrected or to thecharacter to be written again and then writes the new character. Theposition which is marked by the cursor is a particular picture positionto be characterized because changes in the picture content take place inthis position. This position should be marked as clearly as possible;marking must, however, not detrimentally influence the readability of acharacter reproduced in this position. FIGS. 1-3 show how the cursorclearly and simply marks the position by means of inversion of thepicture signal. In FIG. 1 a blank position is marked and in FIGS. 2 and3 a character is marked by the cursor C. FIGS. 1 and 2 show blackwriting on a white background, FIG. 3 shows white writing on a blackbackground. In these examples the separate characters are displayed by araster of seven horizontal and eight vertical picture dots. i

ACCENTUATING CERTAIN PICTURE AREAS OCCUPIED BY SYMBOLS OR CHARACTERS Todistinguish transmitted and received information a changeover from redto black writing is effected, for example, in a teleprinter exchange sothat, for example, the manually fed and transmitted data can bedisplayed black and white and the data transmitted by thedata-processing arrangement can be displayed red on white. The inventionmakes a different display possible in a corresponding manner. Receivedinformation is displayed for example white on black while theinformation originating from the user appears black on white through thesupply station. In FIG. 4 the third line is displayed in white writingon a-black background, the other lines are displayed in black writing ona white background.

VERTICAL LINES Vertical lines can be drawn throughout the picture heightby means of inversion of the picture signal for the duration of one ormore picture dot widths. This makes it possibleto display particularlytabulated additions in a convenient manner. These are efficiently madenarrower than the horizontal interspace between two characters (forexample, one picture dot width) so that the picture content is notdisturbed. The vertical lines may be used as markers for tabulatorpositions, for example, when activating the tabulator function by meansof a special button in the supply keyboard the cursor C moves behind theposition of the next vertical straight line. FIG. 5 shows how such atabulator marking becomes apparent. In white/black picture areas thevertical line V would automatically appear as a white line on a blackbackground.

HORIZONTAL LINES By inverting the picture signal during the period ofthe beam covering the picture in a horizontal interspace the line abovethe space can be underlined (H). In this manner titles can beaccentuated. Tables subdivided or lines which are to be fed into thedata-processing arrangement can be marked. This possibility is shown inFIG. 6.

ACCENTUATING THE INTERSPACE BETWEEN THE LINES For better readability ofthe displayed text especially of tables or many lines of text it is tobe recommended to subdivide the picture on the screen in horizontalstrips so as to guide the eye during reading. This can be achieved inthat the picture screen has a striplike structure so that-as is shown inFIG. 7the characters appear darkly on a white background while thehorizontal interspaces 2 stand out grey. This darkening" of lighthorizontal interspaces is particularly favorable because the pictureshows a much slighter flickering effect. In a corresponding manner thedark interspace can be brightened to a slight extent in case ofinformation the characters of which are displayed white or black. Inthis manner of display it is additionally found that when the entirebackground is somewhat brightened the viewers impression of the pictureis enhanced in a pleasant manner without the readability beinginfluenced. As is referred to under items 1 and 4 in the case ofinversion of the picture signal for the display of a proportionedpicture, this brightening to a slight extent can be employed toaccentuate special portions of the picture, for example, also columns ofarbitrary width in tables, especially when using different grey valueswhose brightness stages are still clearly distinct from one another.

According to FIG. 8 a control signal BAS (composed of a picture signalB, a blanking signal A and a synchronizing signal S) is produced for aTV-monitor TV functioning in accordance with a television standard. Acounter circuit comprising a column counter SpZ, a character counterZchZ, a scanning line counter L2 and a reading line counter ZIZ iscontrolled by a clock signal generator TO. The column counter SpZcontrols the columns of the raster in the picture field for the displayof a character, the character counter ZchZ controls the position of thecharacters in a reading line; the scanning line counter LZ controls theseparate scanned lines in a character (horizontal scanning paths of theelectron beam); the reading line counter ZIZ determines the readinglines in the overall field of display. This counter circuit controls ablanking stage A, a synchronizing stage Sy and a control stage St. Thestage A produces the picture blanking pulses and the stage Sy producesthe synchronizing pulses while the control stage Sr, which is likewisecoupled to the clock-signal generator TG, controls a memory Sp and acharacter generator ZG coupled thereto. The picture signal B, that is tosay, the character control signal from the character generator ZG isapplied through an inverter stage CI, which is active or not active inaccordance with the user's choice, to an input of a gate D to a secondinput of which the blanking signal A is applied. In case of characterdisplay the inverter stage CI serves for generating a cursor, aconspicuous picture area, horizontal or vertical straight lines and forvarying the picture background. The combined picture-blanking signal(BA) and the synchronizing signal (S) are combined in a mixer stage M toform a picture-blanking-synchronizing signal (BAS). The characters to bedisplayed are kept available in the memory Sp. Information is exchangedbetween memory Sp and a dataprocessing arrangement through the line E/Awhile the user can vary the picture content through a keyboard Ta and alead T. The characters coded with minimum redundance in the memory Spare converted into a picture signal B by the character generator ZGwhich for this purpose supplies the corresponding modulation voltage forthe electron beam in the monitor TV.

FIG. 9 shows the block diagram for the generation of a cursor. Thepositions of cursor counters ZCl and ZC2 which positions can be chosenmanually through the keyboard Ta (denoted by key-contacts Cl and C2) arecompared in two comparison arrangements VC] and VC2 with the positionsof the character counter ZchZ and the reading line counter ZIZ. In caseof equal positions of the counters which are interconnected through thecomparison arrangements, a signal is applied through an AND-gate U to acursor control stage CS1. The vertical dimension of the cursor on thepicture screen is limited by the scanning line counter LZ at thecharacter height plus, for example, one line above and below thecharacter. The cursor control stage CS! controls the inverter stage CIwhich inverts the picture signal B provided by the character generatorZG (FIG. 8) for the fixed d uration by means of switching on thisinverter stage CI(B or B).

FIG. 10 shows the structure of the different components in details.NAND-gates 1, 2 and 3 and 6, 7 and 8, respectively compare the positionsof the counters ZchZ and ZCl and ZIZ and ZC2 in the comparisonarrangements VC1 and VC2. Since these counters comprise differentdivider stages employing flip-flops, a switching group corresponding tothe NAND- gates l, 2, 3 and 6, 7, 8 respectively is necessary for eachpair of flip-flops, the output of said NAND gates being connected to aninput of NAND-gates 4 and 5, respectively provided with various inputs.The gate 4 thus marks the column, the gate 5 marks the reading line andhence a NAND-gate 11 connected through two inverters 9 and 10 to theoutputs of the gates 4 and 5 marks the position where the cursor isdisplayed on the picture screen. The width of the cursor is equal to thewidth of the character which is normally to be displayed plus every timehalf a horizontal interspace in front of and behind the character. Theheight of the cursor is deten'nined by the control stage CS! in that thegate 11 is connected through an inverter 12 to a NAND-gate 15 to adifferent input of which the line counter L2 is connected through an SRflip-flop (Set- Reset flip-flop, i.e., bistable multivibrator) formed byNAND- gates 13 and 14 so that the cursor is limited to the desirednumber of scanning lines. The NAND-gate 15 is connected directly andthrough an inverter 17 to NAND-gates l9 and 18, respectively in theinverter stage CI. The picture signal B is applied through an inverter16 and directly to the gates 18 and 19, respectively the outputs ofwhich are connected to the inputs of a NAND-gate 20. The inverter stageCl controls the picture signal B in such a manner that it arrives at themixer stage M during the normal picture display through the gates 19, 20and hence in noninverted form (B), whereas it is inverted (B) throughthe gates l6, 18, 20 for the period of the display of the cursor.

Arrangements for proportioning the picture with the aid of accentuatedpicture areas, vertical and horizontal lines as well as grey stripes arefurther described in principle only.

FIG. 11 shows an arrangement by which arbitrary picture areas can beinverted. The counters ZchZ, LZ and ZIZ correspond to those of FIG. 8.The character counter ZchZ is connected to a decoder D1 which is alsoconnected to the control stage St. The scanning line counter LZ and thereading line counter ZIZ are connected to a decoder D2 which is likewiseconnected to the control stage St. The counters influence the decodersD1, D2 in such a manner that the commencement and the end of theinversion range for the horizontal (ah and eh, respectively) andvertical (av and ev, respectively) directions are fixed by the controlstage St. Two SR flip-flops formed from NAND-gates 21, 22 and 23, 24 andconnected to the decoders D1 and D2 control an inverter stagecorresponding to CI of FIG. 10 through an AND gate function (NAND-gate25). Since the control stage St is connected to the memory Sp for theoverall picture contents, different arbitrary large picture areas can beinverted therein in case of a corresponding arrangement, for example,when more bits are added for proportioning the picture for each readingline.

FIG. 12 shows an arrangement for generating horizontal or verticalstraight lines on the picture screen. The operation corresponds inprinciple to that of the circuit arrangement according to FIG. 11. Inthis case, however, there are no SR flipflops necessary since only oneTV reading line and the raster dots of a column of the raster areinverted. The column counter SpZ and the character counter ZchZ areconnected to a column decoder DSP, the decoder being denoted by DZ forthe counters L2 and ZlZ. The column decoder DSP and the reading linedecoder DZ act on an inverter stage, correspond ing to Cl of FIG.through an OR-gate 26.

The arrangements described may alternatively be used to control the greyhue of the picture background. FIG. 13 shows an example of the mixturestage M (see FIG. 8) which is extended in such a manner that a greycontrol stage G makes a dark picture background lighter and a lightbackground darker. In the mixer stage M the synchronizing signal Scontrols a transistor T,, the picture suppression signal BA controls atransistor T The emitter electrode of transistor T is connected directlyto ground while that of transistor T is connected to ground through avariable resistor P parallel to a collector-emitter circuit of atransistor T in series with a resistor R The collector electrodes of thetransistors T and T and of a transistor T, whose emitter electrode isconnected to ground through a variable resistor P are connected througha resistor R, to a terminal conveying the voltage +V and are in thatcase coupled to the monitor TV. The base electrodes of the transistors Tand T are coupled to the grey control stage G. The black level is fixedby the resistor R when transistor T conducts. Normally transistor Tconducts and transistor T, does not conduct, lf grey values are to beproduced on a black background the transistor T is cut off and thedegree of brightness increase can be adjusted with the aid of thevariable resistor P,. If grey values are to be produced on a lightbackground the transistor T, becomes conducting and the degree ofdarkening can be adjusted with the aid of the variable resistor P Thecommencement and the end of the variation in grey hue is passed on bythe control stage St through leads a and e to the grey control stage G,but it should be taken into account that grey control must not occurduring the suppression signals A less the porches of the synchronizingpulses S are tampered with. In addition, a control input g must receivea l signal from the control stage St in case of black writing on a lightbackground and a 0 signal in case of light writing on a dark background.The control input g is connected directly and through an inverter 27 toNAND-gates 28 and 29, respectively. The other inputs of the gates 28 and29 are connected to the output of an SR flip-flop formed from NAND gatesthe inputs of which are connected to the leads a and e. The output ofthe gate 29 leads to the transistor T while that of gate 28 leads totransistor T through an inverter 30.

What is claimed is:

1. An arrangement for displaying characters or symbols on a screen of adisplay device, which arrangement comprises a clock-signal generator, acounter circuit connected to said generator, a control stage which isconnected to said generator, said counter circuit and a character orsymbol memory, outputs of said control stage and said memory connectedon a character generator having an output for periodically supplyingmodulation voltages corresponding to the characters or symbols of thememory to the display device, the arrangement further comprising a stagefor accentuating characters or symbols on the screen, characterized inthat the said stage for accentuating characters or symbols comprises aninverter stage (Cl) which is connected between the character generator(ZG) and the display device (TV) and which inverter stage (Cl) isconnected so as to be controlled to the said counter circuit whichcomprises a column counter (SpZ), a character counter (ZchZ), a scanningline counter (L2) and a reading line counter (ZIZ) 2. An arrangement asclaimed in claim 1, wherein the display device (TV) comprises atelevision picture tube which is connected to the output of a mixerstage (M), which mixer stage (M) is connected to a blanking stage (A)and to a synchronizing stage (Sy), which are controlled by the countercircuit, and to the character generator (ZG) through the inverter stage(Cl).

3. An arrangement as claimed in claim 1, further compnsmg comparisonarrangements (VCL, VC2) are connected to the character counter (ZchZ)and the reading line counter (ZIZ), respectively, which arrangements arein addition connected to counters (ZCl, ZC2) which can be chosen throughkeys (C1, C2) and which comparison arrangements are both connectedthrough an AND gate (W) to a cursor control stage (CS1) to which theinverter stage (Cl) is connected.

4. An arrangement as claimed in claim 3, wherein the cursor controlstage (CSt) comprises a bistable multivibrator (13, 14) which iscontrolled by the scanning line counter (LZ), the output of saidmultivibrator being coupled through a NAND gate (15) to the output ofthe comparison arrangements (VCl, VC2).

5. An arrangement as claimed in claim 2, wherein the comparisonarrangements (VCl, VC2) comprise successively connected NAND gates (l to10) which are connected together through a further NAND gate (11).

6. An arrangement as claimed in claim 1, wherein a decoder (D1)controlled by the control stage (St) is connected to the charactercounter (ZCHZ) and that a second decoder (D2) controlled by the controlstage (St) is connected to the scanning line counter (L2) and thereading line counter (ZIZ), the outputs of the decoders (D1, D2) beingconnected to bistable multivibrators (21, 22; 23, 24) the outputs ofwhich are connected through a NAND gate to the inverter stage (CI).

7. An arrangement as claimed in claim 1, wherein the column counter(SpZ) and the character counter (ZchZ) are connected to a column decoder(DSP), and that the scanning line counter (L2) and the reading linecounter (ZIZ) are connected to a reading line decoder (DZ), the outputsof the decoders (DSP, DZ) being connected through an OR gate (26) to theinverter stage (Cl).

8. An arrangement as claimed in claim 2, wherein two transistor stages(T T T which are adjustable in amplification are provided in the mixerstage (M) for the purpose of varying the grey hue of the picturebackground, the inputs of said transistors being connected through NANDgates (G and SR) to the control stage (St).

1. An arrangement for displaying characters or symbols on a screen of adisplay device, which arrangement comprises a clocksignal generator, acounter circuit connected to said generator, a control stage which isconnected to said generator, said counter circuit and a character orsymbol memory, outputs of said control stage and said memory connectedon a character generator having an output for periodically supplyingmodulation voltages corresponding to the characters or symbols of thememory to the display device, the arrangement further comprising a stagefor accentuating characters or symbols on the screen, characterized inthat the said stage for accentuating characters or symbols comprises aninverter stage (CI) which is connected between the character generator(ZG) and the display device (TV) and which inverter stage (CI) isconnected so as to be controlled to the said counter circuit whichcomprises a column counter (SpZ), a character counter (ZchZ), a scanningline counter (LZ) and a reading line counter (ZlZ)
 2. An arrangement asclaimed in claim 1, wherein the display device (TV) comprises atelevision picture tube which is connected to the output of a mixerstage (M), which mixer stage (M) is connected to a blanking stage (A)and to a synchronizing stage (Sy), which are controlled by the countercircuit, and to the character generator (ZG) through the inverter stage(CI).
 3. An arrangement as claimed in claim 1, further comprisingcomparison arrangements (VCL, VC2) are connected to the charactercounter (ZchZ) and the reading line counter (ZlZ), respectively, whicharrangements are in addition connected to counters (ZC1, ZC2) which canbe chosen through keys (C1, C2) and which comparison arrangements areboth connected through an AND gate (W) to a cursor control stage (CSt)to which the inverter stage (CI) is connected.
 4. An arrangement asclaimed in claim 3, wherein the cursor control stage (CSt) comprises abistable multivibrator (13, 14) which is controlled by the scanning linecounter (LZ), the output of said multivibrator being coupled through aNAND gate (15) to the output of the comparison arrangements (VC1, VC2).5. An arrangement as claimed in claim 2, wherein the comparisonarrangements (VC1, VC2) comprise successively connected NAND gates (1 to10) which are connected together through a further NAND gate (11).
 6. Anarrangement as claimed in claim 1, wherein a decoder (D1) controlled bythe control stage (St) is connected to the character counter (ZCHZ) andthat a second decoder (D2) controlled by the control stage (St) isconnected to the scanning line counter (LZ) and the reading line counter(ZlZ), the oUtputs of the decoders (D1, D2) being connected to bistablemultivibrators (21, 22; 23, 24) the outputs of which are connectedthrough a NAND gate to the inverter stage (CI).
 7. An arrangement asclaimed in claim 1, wherein the column counter (SpZ) and the charactercounter (ZchZ) are connected to a column decoder (DSP), and that thescanning line counter (LZ) and the reading line counter (ZlZ) areconnected to a reading line decoder (DZ), the outputs of the decoders(DSP, DZ) being connected through an OR gate (26) to the inverter stage(CI).
 8. An arrangement as claimed in claim 2, wherein two transistorstages (T2, T3; T4) which are adjustable in amplification are providedin the mixer stage (M) for the purpose of varying the grey hue of thepicture background, the inputs of said transistors being connectedthrough NAND gates (G and SR) to the control stage (St).